A Gradient of Potential for Modifying Craniofacial Growth

Effects of endocrine disorders on maxillary and mandibular growth in Colombian children and adolescents: a cross-sectional study

OBJECTIVE

To establish the influence of overweight/obesity, medicated hypothyroidism, and medicated non-syndromic hypogrowth on maxillary and mandibular growth.

MATERIALS AND METHODS

The relation between 10 craniofacial anthropometric measurements and hypothyroidism (n = 216), overweight/obesity (n = 108), and non-syndromic hypogrowth (n = 250) were evaluated in patients aged 1-19 years and a control group of healthy patients (n = 587). A subgroup analysis was performed at the peak growth in all groups.

RESULTS

Patients with overweight/obesity and hypothyroidism showed increased craniofacial growth, while hypogrowth patients showed differences in zygomatic width and nasal base growth. Females with hypothyroidism and non-syndromic hypogrowth showed decreased head circumference at peak growth. Several anthropometric measurements were increased in patients with overweight/obesity, including head circumference. When all age groups were analyzed, overweight/obese and hypothyroidism patients showed increased zygomatic width while decreased hypogrowth. Overall, most craniofacial anthropometric measurements in overweight/obese patients were increased. Finally, the peak growth in males with hypothyroidism and subjects with non-syndromic hypogrowth was delayed compared to the control group (p < 0.05).

CONCLUSIONS

Children and adolescents with overweight/obesity and endocrine disorders showed alterations in craniofacial growth. Clinicians must be aware that the growth peak in these patients may be delayed when planning maxillary and mandibular orthopedic treatment.

Anatomic development of the upper airway during the first five years of life: A three-dimensional imaging study

PURPOSE

Normative data on the growth and development of the upper airway across the sexes is needed for the diagnosis and treatment of congenital and acquired respiratory anomalies and to gain insight on developmental changes in speech acoustics and disorders with craniofacial anomalies.

METHODS

The growth of the upper airway in children ages birth to 5 years, as compared to adults, was quantified using an imaging database with computed tomography studies from typically developing individuals. Methodological criteria for scan inclusion and airway measurements included: head position, histogram-based airway segmentation, anatomic landmark placement, and development of a semi-automatic centerline for data extraction. A comprehensive set of 2D and 3D supra- and sub-glottal measurements from the choanae to tracheal opening were obtained including: naso-oro-laryngo-pharynx subregion volume and length, each subregion's superior and inferior cross-sectional-area, and antero-posterior and transverse/width distances.

RESULTS

Growth of the upper airway during the first 5 years of life was more pronounced in the vertical and transverse/lateral dimensions than in the antero-posterior dimension. By age 5 years, females have larger pharyngeal measurement than males. Prepubertal sex-differences were identified in the subglottal region.

CONCLUSIONS

Our findings demonstrate the importance of studying the growth of the upper airway in 3D. As the lumen length increases, its shape changes, becoming increasingly elliptical during the first 5 years of life. This study also emphasizes the importance of methodological considerations for both image acquisition and data extraction, as well as the use of consistent anatomic structures in defining pharyngeal regions.

Skeletal effects of the alteration of masseter muscle function

Aim

To investigate the effects of muscle denervation and the introduction of the β2-adrenoceptor agonist, formoterol, on the relationship between muscles and underlying skeletal growth.

Method

Thirty-one (4-week-old) male Sprague-Dawley rats were assigned to four groups: Surgical Sham; Denervated; Denervated +β2-agonist; and β2-agonist only. The Surgical Sham group had the left masseteric nerve exposed but not sectioned. Both of the denervated groups had the left masseteric nerve exposed and sectioned. The groups receiving the β2-agonist had formoterol directly injected into the left masseter muscle every three days for eight weeks. Sixteen angular and linear skeletal measurements were assessed in the overall craniofacial region and the mandible via standardised digital radiography in three views: lateral head, submento-vertex and right and left disarticulated hemi-mandibles.

Results

The findings indicated that, following surgical denervation of the masseter muscle, there were significant changes in the muscle and in the subsequent development of the underlying skeletal structures. The post-surgical changes were largely offset by the administration of a β2-agonist, formoterol, which attenuated muscle atrophy. However, the administration of the β2-agonist only, without surgical denervation, did not lead to changes in skeletal facial form.

Conclusions

Denervation atrophy of the masseter muscle results in statistically significant changes in the development of the underlying skeleton. The changes, however, are localised to areas of muscle attachment. The administration of the β2-agonist, formoterol, despite its effect on muscle anabolism, does not have a significant effect on underlying skeletal growth.

Genetic expression of MMP-Matrix-mettalo-proteinases (MMP-1 and MMP-13) as a function of anterior mandibular repositioning appliance on the growth of mandibular condylar cartilage with and without administration of Insulin like growth factor (IGF-1) and Transforming growth factor-B (TGF-β)

OBJECTIVE

To determine if the mandibular condylar cartilage (MCC) will grow with and without mandibular anterior repositioning appliances with the administration of insulin-like growth factor (IGF-1) and transforming growth factor-β (TGF-β).

MATERIALS AND METHODS

Twenty-four growing New Zealand rabbits were divided into three groups: a group with saline injection in the temporomandibular joint, a group that received anterior positioning appliance, and a group that received injection of growth factors as well as mandibular repositioning appliance. Real-time reverse transcription polymerase chain reaction technique was used to study gene expression supported by histomorphometry.

RESULTS

Administration of growth factors along with mandibular repositioning appliances has induced 5.70-fold expression of matrix metalloproteinase-1 (MMP-1) (P < .0005) and 1.29-fold expression of MMP-13 (P < .0005). In contrast, administration of mandibular repositioning appliances only has induced 2.33-fold expression of MMP-1 (P < .0005) and 0.83-fold expression of MMP-13 (P < .0005). Histomorphometric analysis revealed increased proliferation of the condylar cartilage in the appliance and injection group as compared to the control group.

CONCLUSION

The administration of growth factors along with the use of mandibular advancement appliance has increased genetic expression of MMP-1 and MMP-13 supported by histomorphometric evidence indicating growth of condylar cartilage.

A mixed longitudinal anthropometric study of craniofacial growth of Colombian mestizos 6-17 years of age

The purpose of this study was to evaluate the craniofacial growth of Colombian mestizos. Four age cohorts, including a total of 458 children and adolescents (262 males and 216 females), were included in this mixed-longitudinal study. The cohorts were first measured at ages 6, 9, 12, and 15 and every year thereafter for 3 years. Eight anthropometric measurements were taken, including three cranial (head perimeter, head width, and head length), two craniofacial (maxillary and mandibular length), and three facial (face height, bizygomatic width, and bigonial width). Multilevel analyses showed that all dimensions increased between 6 and 17 years of age. The cranium grew less than the craniofacial, which in turn grew less than the facial dimensions. In addition, vertical dimensions showed more growth than antero-posterior dimensions, which in turn grew more than transverse dimensions. None of the measurement showed statistically significant growth differences between subjects with normal occlusion and Class I or Class II malocclusions. Males were generally larger than females and showed greater growth rates. Except for facial width, whose yearly velocities decreased regularly with age, an adolescent growth spurt was evident for most of the male measurements. Yearly velocities for females followed a simpler decelerating pattern. The results provide reference data for Colombian mestizos, for whom normative data of other ethnic groups are not applicable. While occlusion had little or no effect, there were gender differences, as well as important growth differences between cranial and facial measurements.

Developmental connections between cranial components and the emergence of the first permanent molar in humans

The age of emergence of the first molar (M1) is a developmental event correlated with many variables of primate life history, such as adult brain size. The evolution of human life history is characterized by the inclusion of childhood, which takes place between weaning and M1 emergence. Children still depend on adults for nutrition due to their small digestive system and their immature brains. By contrast, juveniles are not dependent because of M1 emergence, which enables shifting to adult type diet, and attainment of nearly adult brain size. In this study, developmental connections between M1 emergence and growth of cranial components were explored in two ways in order to understand the developmental basis of their evolutionary connections: (1) differences in growth trajectories of cranial components with respect to M1 emergence and (2) differences between individuals with and without fully emerged M1. Growth of anteroneural, midneural, posteroneural, otic, optic, respiratory, masticatory and alveolar cranial components was analysed in human skulls of individuals aged 0-20 years and in an adult reference skull. Volumetric indices were calculated to estimate size. Two subsamples were selected in order to focus on the transition between deciduous and permanent dentition: those with full deciduous dentition and before M1 reaches the occlusal plane; and those who present M1 in full emergence and no other cheek-tooth at the occlusal plane. The principal results were as follows. (1) Trajectories fitted using the whole sample are characterized by an inflection point that takes place before M1 emergence for neural components and around M1 emergence for facial components. (2) Associations between growth and age tend to be strong in those with full deciduous dentition, and weak in those who present M1 in full emergence. (3) Individuals who present M1 in full emergence are larger than those with full deciduous dentition. (4) Growth of components linked to the central nervous system is not linear until M1 emergence. Individuals who present M1 in full emergence are only larger than individuals with full deciduous dentition by 4-5% of adult size. (5) The alveolar component does not show increments between full deciduous dentition and M1 emergence. (6) When volumetric indices were standardized by age, the growth trajectories of individuals with full deciduous dentition and of those with M1 were not decoupled. In general terms, M1 emergence does not show a strong association with growth of the components that may explain differences in life histories. However, the main changes in neural and alveolar components occur in the first 3 years of life, which may be developmentally connected with M1 crown formation.